VSN-2885/ fix form validation, list refresh, and fuel card supplier filtering
- improved the vehicle and fuel card attribution forms by making required field errors visible with red borders instead of just showing a generic toast message.
- prevent submissions when the fuel type is missing. The brand and model lists refresh automatically after a successful add or edit, and the fuel supplier (pétrolier) field is disabled until a fuel type is selected—only active suppliers appear in its dropdown.
- fixed a bug that was incorrectly clearing the form after a failed save and removed duplicate global Save/Cancel buttons in add mode